I am also having this issue with the Android version; instead of installing, it tries to install an update to an existing app, which I do not have as this' also my first time downloading this VN.
FYI to anyone new to TToF that is having issues installing the Android version: If you have the Lunateria demo installed, you'll need to uninstall it first to install ToFF, cause both packages share the name of "com.org.androidset" :-/